Endoscopic procedures for treating abnormal pathologies within the alimentary canal system and biliary tree (including the biliary, hepatic, and pancreatic ducts) are increasing in number. The endoscope provides access to the general area of a desired duct using direct visualization. However, the duct itself must be navigated using a catheter in conjunction with a guidewire under fluoroscopy. A wide variety of catheters are known for treatment of such targeted anatomical regions. Examples of biliary catheters are disclosed in U.S. Pat. No. 5,921,971 to Agro et al. and PCT International Publication No. 00/69498 to De Toledo et al., the disclosures of which are hereby incorporated by reference.
Agro et al. disclose a catheter for use in biliary procedures, wherein the catheter includes a shaft having a proximal end and a distal end. A guidewire lumen extends through the shaft from a proximal guidewire port located proximal of the distal end of the shaft, to a distal guidewire port located at the distal end of the shaft. The shaft may also include a slot or channel extending from a proximal end of the shaft to the proximal guidewire port. Catheters incorporating such a guidewire opening and channel are often referred to as rapid exchange or single-operator-exchange type biliary catheters.
De Toledo et al. disclose a single operator drainage catheter delivery system including a guide member having a guidewire lumen extending through a distal portion thereof, with a proximal guidewire port located distal of the proximal end. A placement catheter disposed over the guide member has a catheter lumen extending through a distal portion thereof, with a proximal guidewire port located distal of the proximal end. Locating the proximal guidewire ports as such allows the delivery system to be used by a single person with a shorter guidewire. A drainage catheter (a.k.a. a plastic stent) is disposed about the guide member distal of the placement catheter. The drainage catheter delivery system preferably includes a means for releasably connecting the placement catheter to the drainage catheter, wherein the releasable connecting means disconnects the drainage catheter upon displacement of the guide member. However, De Toledo et al. '498 does not disclose a rapid exchange biliary catheter system for the delivery of a metallic self-expanding stent, which requires a retractable sheath.
U.S. Pat. No. 5,484,444 to Braunschweiler et al., and U.S. Pat. No. 5,709,703 to Lukic et al. disclose a stent delivery device which has an elongated sheath with a self-expandable stent placed in contracted condition within the distal area of the sheath. An elongated core is arranged in the sheath for longitudinal motion relative to the sheath to facilitate stent delivery. However, Braunschweiler et al. '444 and Lukic et al. '703 do not provide a rapid exchange feature as in De Toledo et al. '498.
U.S. Pat. No. 5,743,874 to Fischell et al. discloses a catheter capable of performing balloon angioplasty followed by delivery of a self-expanding stent. The catheter includes an outer sheath which may be pulled back to deploy the self-expanding stent. In one embodiment, the catheter includes a guide wire entry port located just proximal of the stent to permit rapid exchange capability. To provide the guide wire entry port, Fischell et al. '874 provides a sloped plug disposed in the inner tube and an elongate side opening in the outer sheath. The elongate side opening in the outer sheath is necessary to permit retraction of the outer sheath for stent deployment. By providing such a long side opening, a major portion of the inner workings of the catheter are exposed to bodily fluids and interference from other devices, which may compromise performance of the stent delivery catheter. This undesirable feature, in addition to others not specifically mentioned herein, leaves a need for an improved rapid exchange stent delivery catheter.
Gastrointestinal strictures in the duodenum and intestines are known to occur for a variety of reasons, often due to impingement or compression caused by an adjacent tumor. A stent may be placed in an enteral region in order to palliate a gastrointestinal structure, keeping a location from being blocked and allowing a patient to have a more normal diet and lifestyle than would otherwise be possible. For example, a stent may be placed by advancing a guidewire and ERCP catheter through an endoscope working channel into an enteral region for the purpose of contrast infusion. The ERCP catheter can then be withdrawn, and a catheter loaded with a self-expanding stent can be advanced over the guidewire to or near an identified stricture. The stent is then released and self-expands to open the stricture. However, enteral stenting has been performed using over-the-wire devices only.